Re: [Gretl-devel] Preserve row and col names of a matrix after functions

On 3 Nov 2016, at 00:49, Allin Cottrell <cottrell(a)wfu.edu&gt; wrote: On Wed, 2 Nov 2016, Sven Schreiber wrote: > Am 02.11.2016 um 14:47 schrieb Riccardo (Jack) Lucchetti: > >> While we're on the subject: > > You recently have a tendency to use this "speaking of which" phrase to actually do a Monty-Python-esque "and now for something completely different" ... > >> brouht up the fact that it's not immediate, in Hansl, to delete certain row/columns from a matrix. > > Yeah, by coincidence I just answered this (old) question yesterday on Stackexchange (http://stackoverflow.com/questions/37242922/deleting-a-column-in-hansl). > >> but I wouldn't be averse to introducing a function pair like killcol(X, e) and killrow(X, e). Opinions? > > First, it would be an improvement. Second, if at all possible, I would favor some clever extension of the matrix indexing apparatus. For example (just an example, no claim of optimality), X[-3, -2] might return the matrix X without the 3rd row and the 2nd column. I appreciate that you said "no claim of optimality", but I don't think we should use negative indices for the purpose you indicate. Seems to me the de facto standard regarding negative indices in matrix-oriented languages is that they mean, "count from the end, not the beginning", not "drop these rows or columns".